Die bonders are presently in use for the mounting of semiconductor devices, e.g. lasers, LEDs, detectors, transistors and the like, onto substrates. A solder or bonding material is interposed between the semiconductor die and substrate and can be in the form of a solder preform, liquid solder, bonding pads, or layers on the die and/or substrate. The die bonder provides pressure and/or heat to bond the die to the substrate.
Most prior art die bonders include a scrubbing means. Scrubbing is an oscillation (generally in the plane of the solder) of the semiconductor die while in contact with the solder material. Scrubbing action is known to break up the oxide, or skin, which may form on the solder material and generally provides better wetting of the solder to the die. Scrubbing is carried out in a bonding system where heat is the source of energy primarily responsible for bonding to occur. It may also be employed in thermocompression techniques employing heat and pressure. It is distinguished, however, from ultrasonic bonding techniques wherein high frequency oscillations of 15,000 to 20,000 Hertz (Hz) are the primary source of energy to provide bonding.
A typical prior art scrubbing mechanism includes an eccentric cam, which mechanically induces an oscillation between the die and the solder. This mechanical scrubbing has caused problems, however, when used to bond facet emitters such as lasers and LEDs to substrates. A die bonder with a more sensitive, accurate, and controllable scrubbing mechanism has been sought.